"4 Idiots" tells the story of several rural people who went to live in the city and then struggled. Everyone has a history of blood and tears, but it is also an inspirational history. Going to Beijing for fame and fortune, encounter all kinds of strange and unreliable journeys along the way, and finally find the true meaning of life.

During the period of the Republic of China, Zheng Tianhu (played by Wang Xiaohu) ran away with his brother Fatty Lin (played by Cheng Ye) due to rent arrears and mistakenly enters an opera troupe where he is raided by warlord Zhang Dachang (Zhang Jiahao). In order to protect Tianhu and Fatty Lin, the troupe master has no choice but to accept the two brothers as disciples. The two brothers are forced to take on the two brothers as apprentices in order to protect them. Will they remain ordinary people? Or will they be men who take up the righteousness of their family and country?

The plot spans nearly 30 years and tells the story of a poor boy from the northeast, "Xiao Bao", who follows his village's hairdresser, "Er Ge" (Sha Yi), to Shenzhen, a special zone. The two are forced to take care of the baby, and then they meet up with a cold-hearted young woman named Ma Lu (Ma Li).

Ma Liu has a happy family, but a paternity test leads him to learn that his son may not be "his own", and in a fit of grief, he and his wife Niu Yun engage in a battle of wits.

Lao Gang, Mule and Dong Yi are brothers who have been friends for decades. As the "big brother", Lao Gang has been "covering" for the vendors in the market, but the arrival of a new boss puts his position in jeopardy. Dong Yi and his wife Feng Lai were originally in a harmonious relationship, but Lao Gang and his mule mistakenly suspect Feng Lai of cheating on them, and they secretly investigate out of brotherly loyalty. Will Lao Gang be able to regain his dignity as the "No. 1 in the vegetable market"? Will Dong Yi and Feng Lai's marriage survive the test? The three veterans of the Northeast are united in a story of love and justice, laughter and tears.